<PRE><B>Question 576149</B>
Plane  	speed	=	200	m/h														
Wind   	speed	=	x	m/h														
																		
against wind =200-x													
with wind  =200	+x 													
																		
Total distance =800	miles	Total Time=	8.30	hours  											
Time upstream + time downstream =8.3 hours																		
																		
800/(200-x)+800/(200+x)=8.3						
800(200	+x)+800	(200-x)=8.30(40000-X^2	)
160000+	800x+160000-800x=332000	-8.3X^2						
320000	--332000=-8.3	X^2											
12000	=8.3	X^2														
	
x={{{sqrt(12000	/8.3)}}}												
x=	38.02	mph															
</PRE>